Liquid pump

ABSTRACT

A liquid pump is proposed, in particular for household machines, such as dishwashers, washing machines or the like, with a pump casing ( 1 ), with a pump casing ( 1 ) incorporating a pump chamber ( 2 ), in which an impeller ( 3 ) is rotatably mounted, and with a drive motor ( 4 ) comprising a rotor ( 5 ) and a stator ( 6 ), wherein the stator ( 6 ) is separated from the rotor ( 5 ) in a liquid-tight manner by the wall ( 7 ) of a rotor chamber ( 8 ), which avoids or at least diminishes the aforementioned disadvantages while retaining the advantages of a wet runner. This is achieved according to the invention by providing a thermally conductive separating wall ( 9 ) between the pump chamber ( 2 ) and the rotor chamber ( 8 ).

The invention relates to a liquid pump according to the preamble toclaim 1.

Liquid pumps, in particular for household machines, dishwashers, washersor the like, are already commercially available in so-called wet-runningmodels. The rotor of the motor is here incorporated in a rotor chamber,the casing wall of which separates the stator from the rotor in aliquid-tight manner. The rotor chamber is here connected relative to thepump chamber inside the pump casing in such a way as to allow liquidthrough, so that an exchange of liquid or water takes place. The casingof the rotor chamber is often also referred to as a slit tube, since itextends through the annular gap between the rotor and stator.

The design of a wet runner leads to a higher efficiency in thisapplication, since the liquid or water is utilized to cool the motor, sothat the exhaust heat of the motor is used to warm the liquid or water.A corresponding amount of energy can be saved during subsequent heatingprocesses.

In addition, this design offers a good insulation for the stator,yielding advantages relating to the production and assembly of thestator, and of the electrical connections.

However, the disadvantage to conventional wet runners is that theliquid-exposed connection of the rotor chamber to the pump chamber cancontaminate the rotor chamber. In addition, the rotor chamber along withthe pump chamber is evacuated when not in operation.

By contrast, the object of the invention is to propose a liquid pumpthat avoids or at least diminishes the disadvantages mentioned abovewhile retaining the advantages to a wet runner.

This object is achieved based on a liquid pump of the kind mentioned atthe outset by the characterizing features in claim 1.

The measures specified in the subclaims enable advantageous embodimentsand further developments of the invention.

Consequently, one liquid pump according to the invention ischaracterized in that a thermally conductive separating wall is providedbetween the pump chamber and rotor chamber.

This measure enables embodiments in which the transfer of liquid, andhence dirt, from the pump chamber into the rotor chamber is reduced, oreven entirely prevented in extreme cases, while retaining the coolingfunction and exhaust heat utilization.

In the further development last mentioned, an at least temporarilyliquid-tight separating wall is provided between the pump chamber androtor chamber. This separating wall completely decouples the rotorchamber from the pump chamber, and hence from the circulating liquid,during pump operation, at least in the closed time intervals. Thiscompletely precludes any contamination by the circulating liquid withrespect to the rotor chamber. The thermally conductive design of theseparating wall ensures that the advantages of the wet runner areretained, i.e., good motor cooling and exhaust heat utilization.

To improve the transport of heat from the rotor chamber into the pumpchamber, a surface-enlarging structure is preferably provided for theseparating wall. Such a surface-enlarging structure can be realized, forexample, via appropriate shaping, i.e., in the form of grooves, zigzagprofiles or the like. It would also be conceivable to introduce ribs orthe like in the transitional area between the rotor chamber and pumpchamber.

In a preferred embodiment, however, only the cross section of the rotorchamber is expanded in the area of transition to the pump chamber,thereby enlarging the surface of the separating wall to the pumpchamber. In comparison to the aforementioned embodiments withsurface-enlarging structures in the pump chamber, this embodiment betterfacilitates flow, and can also be manufactured more easily, and henceless expensively.

In order to utilize the advantages of a wet runner, the rotor chambermust be filled, at least during startup. This can take place during pumpassembly, for example.

However, in a particularly advantageous embodiment of the invention, therotor chamber is first filled when starting up the pump. To this end,the separating wall is preferably provided with a passage through whichthis filling takes place.

In addition, if air unexpectedly gets into the area of the rotorchamber, a corresponding passage can be used in a further development ofthis embodiment for renewed filling with liquid or water.

In a further development of this embodiment, the rotor chamber isprovided with a valve to enable filling of the rotor chamber whileproviding a liquid-tight seal between the rotor chamber and pump chamberduring operation. Such a valve can be used to open a passage for fillingpurposes, and again close it during operation.

It is also advantageous to provide the rotor chamber with a vent valveto facilitate filling, e.g., during initial startup or given anundesired evacuation of the rotor chamber. In a special embodiment, sucha vent valve can interact with a correspondingly small and suitablyarranged open fill hole in such a way that liquid is only resuppliedduring the simultaneous removal of air through the vent valve.

In an advantageous embodiment, the fill valve for the rotor chamber isdesigned as a floater, thereby enabling an automatic evacuation andrefilling of the rotor chamber via the pump circulation.

An advantageous further development provides for the controlled fillingof the rotor chamber with liquid, e.g., water, via the pump circulation.This control can be implemented as a function of various parameters. Inthis case, control can take place via an independent valve or anactuated valve, for example. The valve can here be designed forelectromagnetic, mechanical or even hydraulic actuation, for example.

In a special embodiment of the invention, rotor chamber filling isactuated as a function of the presence of air in the rotor chamber.Among other ways, this can take place, for example, by way of anautomatic vent valve in conjunction with a float valve, for example, inthe separating wall between the rotor chamber and pump chamber withoutexternal actuation. However, controlled, air-dependent refilling bymeans of an air sensor, e.g., a floater, a light barrier or the like, isalso conceivable.

It is further conceivable that the rotor chamber be filled as a functionof temperature. In this case, it would be possible to use a valve, e.g.,comprising a thermostat, thereby permitting liquid to pass into therotor chamber if a threshold temperature has been exceeded. As aconsequence, if the rotor chamber is evacuated, e.g., as the result ofleaks, so that sufficient cooling is no longer ensured, the temperatureincreases accordingly in that location until a filling with liquid takesplace via the pump circulation. Such a temperature-dependent fillingwould also be conceivable in another embodiment with a temperaturesensor and an external actuation of a corresponding fill valve.

In another embodiment of the invention, the rotor chamber is filleddepending on the rotational direction of the drive motor.

In this case, the axial force exerted by a corresponding pump wheel onthe axis could be used to open or close a passage between the pumpchamber and the rotor chamber. The rotor chamber would here be filled bybriefly running the motor in a rotational direction opposite the normaloperating state. To this end, a corresponding motor controller could beprovided to initiate rotor chamber filling as a function ofcorresponding state parameters. The axial force can be generated via acorresponding angular adjustment of the impeller blades, for example.

The rotor chamber can also be filled as a function of time, i.e., thepassage between the rotor chamber and pump chamber can be opened atspecific time intervals to ensure that the rotor chamber is alwaysfilled with enough liquid.

The key factor in terms of the invention when contrasted withconventional wet runner pumps is that the necessary thermal transportbetween the rotor chamber and pump chamber is initiated at leastpartially via the thermally conductive function of the separating wall,thereby diminishing, or even entirely avoiding, the liquid exchangebetween the pump chamber and rotor chamber.

One exemplary embodiment of the invention is shown in the drawing, andwill be explained in greater detail below based on the figures.

-   Shown specifically on:

FIG. 1 is a diagrammatic section through a liquid pump according to theinvention with thermally conductive separating wall;

FIG. 2 is a diagrammatic section through a second liquid pump accordingto the invention with ventilation;

FIG. 3 is a diagrammatic section through a third liquid pump accordingto the invention with a rinsing system that operates as a function ofrotational direction, and

FIG. 4 is a diagrammatic section through a fourth liquid pump accordingto the invention with a second rinsing device that operates as afunction of rotational direction.

FIG. 1 diagrammatically depicts a liquid pump or so-called “wet runner”for a dishwashing machine with an inlet 10 and an outlet 11. The wetrunner has a pump casing 1, which incorporates a pump chamber 2 with animpeller 3, and a motor 4 with a rotor 5 and a stator 6. The stator 6 isseparated from a rotor chamber 8 by means of a wall 7.

A thermally conductive separating wall 9, in particular a metal wall 9,is provided between the pump chamber 2 and the rotor chamber 8. Thisseparating wall 9 makes it possible to divert heat of the rotor chamber8 or a fluid provided therein, in particular cooling liquid, into thepump chamber 2 or a pump fluid, in particular water, in an advantageousmanner. A cooling system for the motor 4 according to the invention isthereby realized without potentially contaminated pump fluid or washingwater being able to get into the rotor chamber 8.

In general, the components labeled with the same reference numbers inthe figures are correspondingly comparable.

FIG. 2 shows a variant with a floater 12 for ventilating the rotorchamber 8. For example, the outlet 11 is situated above viewed in anaxial direction. The floater 12 comprises a hole through which any gaspresent in the rotor chamber 8 can escape, in particular air. Theseparating wall 9 or the pump casing 1 can encompass the holes of thefloater 12 in an advantageous manner.

FIG. 3 shows a variant that involves rinsing the rotor chamber 8 as afunction of rotational direction. To this end, the separating wall 9 hasat least one valve 13 with holes that can be opened or closed by meansof a lever mechanism 14. For example, the mechanism 14 encompasses aspring.

The valve 13 is opened and closed when changing the rotational directionof the motor 4 by virtue of the fact that the impeller 3 generates anaxially oriented force owing to an advantageous configuration of theblades. In turn, this force produces a relative movement 15 between theseparating wall 9 and rotor 5, thereby changing the volume of the rotorchamber 8 or the pressure therein. As a result, the mechanism 13 opensand closes the holes in the separating wall 9. With the hole opened, thefluid of the rotor chamber 8 can be changed out in an advantageousmanner.

The variant according to FIG. 4 also exhibits a rinsing system thatoperates as a function of rotational direction. However, the separatingwall 9 here exhibits at least one comparatively large hole 16, which canbe opened and closed by means of a paddle 17 or the like.

Depending on the rotational direction of the rotor 5, the paddle 17 ismoved into a first or second position based on the flow of fluid presentin the rotor chamber 8. FIG. 4 b diagrammatically depicts a cutoutsection in the area of paddle 17. The hole 16 is open in the firstposition (solid line). The paddle 17 covers the hole 16 in the secondposition (hatched line). With the motor 4 turned off, the paddle restsalong the central line 18.

The variants of the invention specified above can basically be combinedas desired.

Reference List:

-   -   1 Pump casing    -   2 Pump chamber    -   3 Impeller    -   4 Motor    -   5 Rotor    -   6 Stator    -   7 Wall    -   8 Rotor chamber    -   9 Separating wall    -   10 Inlet    -   11 Outlet    -   12 Floater    -   13 Valve    -   14 Mechanism    -   15 Movement    -   16 Hole    -   17 Paddle    -   18 Line

1. A liquid pump, in particular for household machines, such asdishwashers, washers or the like, with a pump casing (1) incorporating apump chamber (2), in which an impeller (3) is rotatably mounted, andwith a drive motor (4) comprising a rotor (5) and a stator (6), whereinthe stator (6) is separated from the rotor (5) in a liquid-tight mannerby the wall (7) of a rotor chamber (8), characterized in that athermally conductive separating wall (9) is provided between the pumpingchamber (2) and the rotor chamber (8).
 2. The pump according to claim 1,characterized in that the separating wall (9) is liquid-tight.
 3. Thepump according to one of the previous claims, characterized in that theseparating wall (9) has a surface-enlarging structure.
 4. The pumpaccording to one of the previous claims, characterized in that the crosssection of the rotor chamber (8) has a cross sectional expansion toenlarge the surface of the separating wall (9) to the pump chamber (2).5. The pump according to one of the previous claims, characterized inthat a liquid passage (16) is provided between the pump chamber (2) andthe rotor chamber (8).
 6. The pump according to one of the previousclaims, characterized in that a valve (12) is present for the rotorchamber (8) so that the rotor chamber (8) can be filled.
 7. The pumpaccording to one of the previous claims, characterized in that the valve(12) is provided for opening and closing the passage between the pumpchamber (2) and the rotor chamber (8).
 8. The pump according to one ofthe previous claims, characterized in that a vent valve (12) is providedfor the rotor chamber.
 9. The pump according to one of the previousclaims, characterized in that the valve (12) is designed as a floatvalve (12).
 10. The pump according to one of the previous claims,characterized in that there is a controlled filling of the rotor chamber(8) with liquid.
 11. The pump according to one of the previous claims,characterized in that a control unit is provided for filling the rotorchamber (8) as a function of the presence of air in the rotor chamber(8).
 12. The pump according to one of the previous claims, characterizedin that a control unit is provided for the temperature-dependent fillingof the rotor chamber (8) with liquid.
 13. The pump according to one ofthe previous claims, characterized in that a control unit is providedfor filling the rotor chamber (8) as a function of the rotationaldirection of the drive motor (4).
 14. A household machine, such as adishwasher, washer or the like, characterized in that a pump accordingto one of the preceding claims is provided.